Takeru Omiya^{1, 2}, Albano Cavaleiro^{1, 2}, Fabio Ferreira^{1, 2
1}University of Coimbra, Coimbra, Portugal
²Instituto Pedro Nunes, Coimbra, Portugal
This study introduces a novel lubrication strategy that employs gadolinium-doped diamond-like carbon (Gd-DLC) coatings in tandem with specific ionic liquids to bolster wear resistance and corrosion protection in mechanical systems, addressing the environmental concerns associated with traditional lubrication methods like zinc dialkyldithiophosphates. The research delves into the synergistic effects between Gd-DLC coatings and two particular ionic liquids, illustrating how this combination curtails wear and thwarts corrosion, thereby extending the service life of mechanical components. The study leverages sophisticated analytical techniques, such as X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), to elucidate the mechanisms that enhance this lubrication system's performance.
The results underscore that gadolinium doping in DLC coatings not only elevates wear resistance but also fortifies corrosion protection, especially notable when interfaced with ionic liquids like trihexyltetradecylphosphonium bromide. It was observed that wear rates diminish with an increase in Gd content, and specific ionic liquids, notably [P_6,6,6,14][Br], offer superior wear resistance compared to [P_6,6,6,14][DEHP]. This indicates that the mechanism behind wear resistance in Gd-DLC coatings transcends mere hardness and involves the formation of protective tribofilms, evidenced by increased phosphorus presence on the wear track as detected by XPS and ToF-SIMS.
This study not only demonstrates the potential of Gd-DLC coatings combined with ionic liquids in enhancing wear resistance and providing substantial corrosion protection but also contributes to the development of advanced lubrication systems that are both effective and environmentally sustainable. Such advancements promise to significantly improve the longevity and reliability of mechanical systems while aligning with sustainability objectives.